It is frequently necessary in the course of catheterization procedures and many surgical procedures to insert one catheter or instrument through a passage or lumen in another catheter or instrument. To avoid bleeding or loss of other fluids through the annular space between the two catheters or instruments it is typical to employ a hemostasis valve or other sealing device at the proximal end of the outer catheter or instrument. The inner catheter or instrument is inserted through the hemostasis valve, which creates a fluid tight seal around the inner catheter or instrument. The hemostasis valve may be integrated into the outer catheter or instrument as is typical in the case of introducer sheaths, or it may be provided in a separate connector attachable to the outer catheter or instrument, as is typical for guiding catheters and many other cardiovascular catheters. A common configuration for such valved connectors is a Y-shaped configuration with a main channel that includes a hemostasis valve or other sealing device at its proximal end and a lateral channel that permits injection or aspiration of therapeutic or diagnostic fluids or measurement of pressure.
A problem arises when inserting a fragile or highly flexible catheter or instrument through such a hemostasis valve or sealing device. The fragile catheter or instrument may be deformed or damaged as it passes through the hemostasis valve or sealing device. In addition, many known valved connectors and fittings contain other obstacles to passage of a catheter or instrument, such as internal steps or cavities, abrupt tapers and side passages that may impede, divert or damage the catheter or instrument during insertion. This problem is of particular concern when using extremely flexible or fragile micro-guidewires and micro-catheters or when using assemblies mounted and maintained by friction or crimping, like for example a stent mounted on a balloon of a dilatation catheter.
Hemostasis valves or sealing devices in existing valved connectors can be classified into two types:
The more common type, referred to herein as type 1, includes an active valve that is normally open and is closable by compressing a cylindrical or toroidal seal by means of a threaded cap. Adjusting the closure according to the diameter of the catheter introduced is accomplished by tightening or loosening the threaded cap as shown in FIGS. 1 and 2. Complete closure is possible even in the absence of an instrument introduced in the system.
The advantage of this system is that, when open, the valve provides an open passage for insertion of catheters and instruments. The disadvantage of this system is connected with the principle of the compression sealing mechanism. To permit the movement of the catheters introduced, one must loosen the threaded cap thereby provoking leaking of blood. Equally one must not forget to tighten the threaded cap to reclose the seal. These necessary manipulations are a significant inconvenience to the physician during a catheter procedure. Movement of the inserted catheter without loosening the valve can easily damage a delicate catheter or instrument. In addition, overtightening of the threaded cap can cause damage to the catheter or instrument introduced through the valve.
The other type, referred to herein as type 2, includes a normally closed, passive or hemostatic valve which due to its elasticity and its cut or molded configuration, permits the passage of catheters while maintaining a seal without the necessity of manual adjustments, as shown in FIGS. 3 and 4. In this case, sealing is passive and continuous, and movement of catheter is possible due to the flexibility and the low friction of the valve. Nonetheless, the major problem of the type 2 system imposes itself during the introduction of fine and fragile instruments such as micro-guidewires and micro-catheters or assemblies mounted and maintained by friction or crimping, like for example a stent mounted on a balloon of a dilatation catheter. One must, in this case, utilize a small rigid introduction tube that is pushed across the valve and which permits introduction of fragile instruments through the valve. This tube is then removed and the valve seals around the proximal body of the instrument. The introduction tube remains, of course, in a coaxial position on the proximal body of the catheter introduced and can then cause difficulties for the operator. One foreseeable solution to avoid this problem is using a split introduction tube. However, such a split introduction tube is more fragile and less effective at crossing the valve and protecting the inserted instrument.
Another solution to this problem is to integrate the introduction tube into the connector device. This solution is illustrated in the following patent: U.S. Pat. No. 5,195,980. In this patent, a fitting with a tubular extension is slidably mounted on the proximal end of the valved connector. Sliding the fitting distally with respect to the valved connector causes the tubular extension to penetrate the valve and open it for passage of fluids or instruments. This solution, however, poses two other problems. First, the additional fitting and the tubular extension elongate the valved connector unnecessarily, requiring all of the inserted catheters and instruments to be that much longer, as well. Second, the configuration of these connectors creates internal steps or cavities within the connector that may impede, divert or damage a catheter or instrument during insertion and that may also create a nidus for stagnation and clotting of blood.